Continuous spawning in the cirrate octopods Opisthoteuthis agassizii and O. vossi: features of sexual maturation defining a reproductive strategy in cephalopods

The reproductive strategy of the cirrate octopods Opisthoteuthis agassizii and O. vossi (collected off Namibia from 1988 to 1990) was analyzed. Ovarian oocyte size frequency analysis for both species revealed continuous egg production over the entire adult life span. Mature eggs were stored in the single oviducal gland and distal oviduct, but oviducal gland fullness was not related to body size (p>0.2). All O. agassizii male specimens from 95 to 5400 g total weight were sexually mature, as were all females from 190 to 1650 g, indicating that considerable growth takes place after the onset of sexual maturity. “Continuous spawning” is defined as a single, extended and continuous period of egg maturation and spawning. This model of reproductive strategy is previously unreported in cephalopods. All O. vossi male specimens from 750 to 3050 g total weight, and females from 800 to 1300 g, were sexually mature. Mature males and females of both species were collected in all seasons of the year. The adaptation of cirrate octopods to non-scasonal deep-sea environments is considered. The sexual maturity characteristics of males were analyzed, and examination of the spermatophore revealed opercular structures previously unreported in cephalopods. For females, the micropyle of the eggs are described and the mineral analysis of the egg shell disclosed that sulphur was the major element present